Convert a List of Values
In this tutorial, we review how to convert a list of 1's and 0's into a list of boolean values while introducing several key concepts in Python. There are multiple ways to achieve the conversion in Python. For starters, a for loop with an if/else statement.
integers = [1, 0, 0, 1, 0] # list of 1's and 0's
booleans = [] # empty list
for value in integers: # loop over each integer value
if value == 0: # check if value is equal to 0
booleans.append(False) # append to booleans list
else: # fallback condition
booleans.append(True) # append to booleans list
The code can be reduced with a ternary operator. In C-style syntax, including a language such as JavaScript, a ternary statement looks like x = some_condition ? true : false with symbols to convey meaning. In Python, the syntax is clearer and reads like a sentence in English e.g. x = True if some_condition else False.
Replace the if/else code block from the for loop example with the ternary operator.
integers = [1, 0, 0, 1, 0]
booleans = []
for value in integers:
result = False if value == 0 else True # ternary statement
booleans.append(result)
An alternative approach to the conditional logic is utilizing a dictionary as a key-value conversion mapper.
integers = [1, 0, 0, 1, 0]
booleans = []
mapper = {0: False, 1: True} # key-value conversion mapper
for value in integers:
result = mapper[value] # map the integer to the boolean value
booleans.append(result)
Python includes an expression called a list comprehension to concisely create lists. List comprehensions are suitable for creating lists from short and simple loops.
integers = [1, 0, 0, 1, 0]
mapper = {0: False, 1: True}
booleans = [mapper[value] for value in integers] # list comprehension
Furthermore, Python treats all values as either truthy or falsy, a similar construct found in JavaScript. Integers can be converted into a True/False boolean value using the built-in bool function i.e. bool(0) -> False or bool(1) -> True.
The example code can be further condensed by removing the mapper and converting the integer value into a boolean using the bool function. In effect, a succinct and easily readable implementation with only two lines of code (plus a print statement to view the result).